People are taking notice of Urban Prep’s achievements. Mayor Rahm Emanuel recently gave students a pep talk, while NBA star Dwayne Wade donated $10,000 through his foundation to help pay for the cost of the senior prom.

But some critics say the students in danger of not graduating don’t reach senior year.

“Urban Prep is not for everyone, and those students may leave us,” school founder and CEO Tim King, said. “But the fact that some students choose to leave us should not be used as a weapon against the students who have chosen to stay and have achieved this incredible accomplishment.”

The Chicago school is part of Urban Prep Academies, a nonprofit organization that operates a network of all-boys public schools including the country’s first charter high school for boys, according to the organization’s website.